Something that comes up again and again in front-end accessibility is the issue of links versus buttons. You know, the HTML elements that open links in new windows or submit forms?

A search form with advanced filtering options and quick link suggestions.

A simple and easy to customize contact form.

Auto-hide sticky header is a shot that shoots down two rabbits: makes site navigation easily accessible anywhere on the page and saves content space at the same.

A mobile-friendly pagination component, that can be easily customized using CSS or Sass.

Velocity is an animation engine with the same API as jQuery's $.animate(). It works with and without jQuery. It's incredibly fast, and it features color animation, transforms, loops, easings, SVG support, and scrolling. It is the best of jQuery and CSS transitions combined.

Have a blog? With small adjustments, you can noticeably improve its typography. Your readers will thank you for it.

The complete Elusive Icons 2.0.0 icon reference

Jarallax is an open-source javascript library which makes adjusting css based on interaction easy.
With Jarallax it's easy to create a parallax scrolling website.

There is a certain style of button on the latest YouTube design (most easily found in the footer) where the default state of the button has a very subtle bevel to it, but on :hover and :focus states the button pops up, eager to be clicked.

A javascript library for multi-touch gestures